A failure analysis method and apparatus are used for identifying a failure location on a semiconductor chip such as an LSI chip or the like, and for determining a cause of the failure. A procedure for failure analysis is broadly divided into two. First, a location suspected of failure on a semiconductor chip is focused upon, to the order of microns. Then, the location focused upon is physicochemically destructively analyzed. The following disclosures describe conventional technology related to failure analysis methods and apparatuses of this type.
Conventional Example 1 discloses technology as schematically shown in FIG. 4 (refer, for example, to Non-Patent Document 1, FIG. 3). In a state in which a current flows from a constant voltage source 103 between 2 terminals of an LSI chip 101, an area to be observed is scanned in a state in which a heating laser beam 102 is focused close to a surface of the LSI chip 101. Since the heating laser beam 102 is often radiated from the back side of the LSI chip 101, the drawing is also arranged in that way. When the heating laser beam 102 radiates on a current path (corresponding to 106) on the LSI chip 101, the temperature of wiring at a location thereof rises and wiring resistance changes, so that this change can be detected by a current change detection measuring device 104. By displaying an output signal of the current change detection measuring device 104 as a scan image, visualization of the current path 106 is possible. If there is a defect 105 in the wiring, since the extent of temperature rise is different from locations without the defect 105, a contrast is obtained in the scan image. Using this type of Conventional Example 1, it is possible to visualize the current path 106 on the LSI chip 101 and the defect 105 on the current path 106. Since spatial resolution of the scan image by this method is determined by the diameter of the heating laser beam 102, at maximum, submicron resolution can be obtained.
Conventional Example 2 discloses technology as shown in FIG. 5 (refer, for example, to Patent Document 1). A SQUID fluxmeter 203 is a magnetic sensor with the highest sensitivity at present. When an LSI chip 201 is radiated close to a surface thereof by a photocurrent generation laser beam 202, there is a location in the LSI chip 201 at which photocurrent is generated. The location at which the photocurrent is generated is at and in a vicinity of a location at which there is p-n junction or an impurity concentration difference. When the photocurrent is generated, a magnetic field is generated. This magnetic field is detected by the SQUID fluxmeter 203. The SQUID fluxmeter 203 scans in an area to be observed in a state in which the photocurrent generation laser beam 202 is radiated in a fixed manner at a location at which the photocurrent is generated, and a scan image is obtained. The obtained scan image shows magnetic field distribution, and by a Fourier transform thereof a current distribution image is obtained. “SQUID” is an abbreviation of “Superconducting Quantum Interference Device”.
[Patent Document 1]
JP Patent Kokai Publication No. JP-P2006-258479A
[Non-Patent Document 1]
Measurement from Chip Back Surface by IR-OBIRCH Method, Nikawa, Kiyoshi, and Inoue, Shoji, NEC Technical Report, NEC Corporation, 1997, Vol. 50, No. 6, p. 68-73.